Mat boards with cut sight openings are commonly used for framing photographs, pictures and the like. Numerous forms of manual devices and machines are disclosed in the art, and are commercially available in both professional and also "DIY" (do-it-yourself) models, for cutting both the outside periphery of such mats (normally done with a "straight" cut, at a perpendicular angle) as well as the sight opening (normally done with a "bevel" cut, at an acute angle).
Exemplary apparatus is shown in the following U.S. Pats.: Williams No. 1,250,538, issued Dec. 18, 1917, Umholtz No. 2,924,010, issued Feb. 9, 1960, Meshulam et al No. 4,064,626, issued Dec. 27, 1977, Pierce No. 4,262,419, issued Apr. 21, 1981, Beder No. 4,685,366, issued Aug. 11, 1987, and McGinnis No. 4,986,156, issued Jan. 22, 1991; a system generally more sophisticated than the foregoing is disclosed by Kozyrski et al in No. 4,798,112, issued Jan. 17, 1989. Davidson U.S. Pat. No. 4,831,739, issued May 23, 1989, provides an adjustable template device, for framing and cutting sheet material, in which resilient pins engage lines of detents so as to retard relative sliding movement of adjacent members.
Despite the foregoing, a need remains for a relatively simple and inexpensive assembly in which a manual cutter, capable of operating independently to produce bevel cuts, is readily converted to produce straight cuts.